It may come as a surprise, but with the steamy summer upon us, it’s important to keep mould and mildew considerations in mind when it comes to your home.

David Ewerse, maintenance and janitorial coordinator for Roper’s Enterprises Ltd, is a mould expert who’s seen it all. From homes that were uninhabited for years, to apartments with the air conditioning accidentally left off for a mere few weeks, there’s always a chance mould and mildew may strike, given the right opportunity.

“Mould and mildew have similar characteristics, but they are different types of fungi which are found everywhere inside and outside,” says Ewerse.

“Mould & mildew can grow on almost any substance when moisture and the required warm temperature are present. Mould is often black, green, red, or blue in colour, while mildew is usually gray or white.”

When mould and mildew reproduce, they make spores that can be carried by air currents. When these spores land on a moist surface that is suitable for surviving, they begin to grow. It’s startling to learn that mold and mildew are normally found indoors at levels that do not affect most healthy individuals.

The right conditions

“Mould and mildew growth in an indoor environment is typically related to water or moisture,” says Ewerse.

“For significant mold and mildew growth which is not being shown on my assessment of the apartment, there must be a source of water, which can be invisible humidity.”

Invisible humidity, he explains, can be caused from hot air build-up, especially when the air-conditioning unit is not frequently used or outdoor natural cool air is not flowing inside.

“Both our indoor and outdoor environment has mould and mildew spores present. There is no such thing as a mould- and mildew-free environment in the earth’s biosphere,” he says.

“Moisture will always be the decaying process caused by the mould and mildew. Mould and mildew growth begins between 24 hours and 10 days from the provision of the growing conditions, but cannot be measured to know the age of the mould.”

Pierre Beaudet of Cayman Climate controls says that changes in local construction methods impact mould and mildew.

“The main dehumidifier in your home is your AC unit,” he says.

“For it to work, it has to run for a long period of time. In the past, in Cayman most houses were built from concrete and not well insulated, meaning the AC systems would run and run.”

However, because of the high levels of insulation people are putting in their homes these days in an effort to be more energy efficient, homes stay cooler longer.

That means that the AC units are not running for very long periods of time any more.

Despite this, Beaduet says some homebuilders in Cayman are still using the same size air conditioning units they were using in the past, which is a mistake.

“You need to reduce the capacity of the AC unit so it runs longer. That will allow it to remove humidity as well as cool your house.”

A smaller, modern AC unit, running longer, shouldn’t use any more electricity than a larger counterpart only running sporadically throughout the day.

It’s all about the moisture

The ability of air to hold moisture directly relates to its temperature. The warmer air is, the more moisture it is capable of holding When enough latent heat is removed from water vapour, it condenses into water.

Beaudet notes that humans, as well as houses, are more comfortable in dryer conditions. In addition, when the air is dryer, it doesn’t feel as hot.

In some cases, well insulated homes may well be more humid than the air outside.

“The most expensive aspect of running the AC is changing water vapour to water,” says Beaudet.

“You need to calibrate the AC system to turn the vapour into water so it can be collected and drained more efficiently,” he adds.

“In some places, a perfect setting is 45 to 55 per cent humidity, and you will see system running 2 hours and stopping one hour.”

He notes that some simple decisions, like making sure that ventilation ducts have smooth surfaces so they are less likely to collect moisture, and installing the correct type of air conditioning system upfront instead of having to resort to costly auxiliary dehumidification systems to combat mould and mildew, can make a huge difference.

Recommendations

Move air by using the air conditioning will prevent mould and mildew from growing, since it has the same effect as lowering the humidity inside the apartment.

Keep the indoor temperature at approximately 74 degrees Fahrenheit (23.3 Celsius) or basically lower than the outside temperature, as mould and mildew need a higher temperature to grow and do not like cool conditions.

If not using the air-conditioning unit on a cool night, allow the cool air from outside to flow into the apartment by opening windows.

Do not use the air-conditioning unit with windows open, as this will over- work your AC, and allow hot air to enter, and not allow the thermostat to cut out the AC unit.

Do not allow any build up of dust, as this is a food source for mould and mildew if present, so prevent this by having a proper cleaning schedule.

Keep the AC on auto, set the temp to 74 degrees and the AC will always come on if the humidity and temperature inside gets warmer than 74 degrees.

During the cooler months, the AC unit, when set in auto and at the correct temperature, will most times not come on and increase your electricity consumption. When the warmer months are here, the AC unit will obviously come on more frequently and your electricity consumption will increase.